Γειά σου συμπατριώτη,
Unfortunately, Gearbest has stopped shipping lithium cells to Greece.
The code is working fine but it’s due to the store’s shipping regulations that you can’t complete the order’s procedure.

Yeap.
I don’t know the specific reason (some are speculating that a cell once exploded during transportation), but the fact is that we are out of luck in here!

Not a speculation. It is a fact. See the Wiki page here showing UPS Airlines Flight 6 went down in 2010 due to fire caused by a pallet of Lithium batteries. Following is copied straight out of the Wiki page.

On July 24, 2013,25 the GCAA released the final investigation report. The report indicated that the fire was caused by the autoignition of the contents of a cargo pallet, which contained more than 81,000 lithium type batteries and “other combustible materials”.26

The Samsung Note 7 fiasco last year probably doesn’t help either. And this is coming from a huge Samsung Note fan!